In gas operated high voltage bushings, such as shown in U.S. Pat. Nos. 3,542,986 and 4,088,383, a snuffer tube and female contact carried by a metallic piston are disposed within and connected to a metallic piston cylinder. Under fault current conditions, the tube and contact are pushed onto an incoming probe contact by gas pressure acting against the piston. The entire mass of the snuffer tube, the female contact and the metallic piston must be moved by the gas pressure. In U.S. Pat. No. 4,260,214, a reduction in the mass of the moving parts is achieved through the use of the snuffer tube itself as a piston. The female contacts for the conduction of load current are affixed to the piston cylinder by a press fit, where they remain in stationary position. However, this embodiment requires that an auxiliary set of moving contacts be provided for the extinguishment of a fault current arc.
U.S. Pat. Nos. 3,982,812 and 4,186,985 also show bushing constructions that include massive metallic pistons to push female contacts onto an incoming probe. This use of a metallic piston and a female contact has required a first current conducting connection between the piston and the female contact. In addition, the aforementioned U.S. Pat. Nos. 4,088,383 and 4,186,985 also show flexible contacts positioned between the piston and the confining cylinder, thereby requiring a second conducting connection from piston to flexible contact and a third conducting connection between the flexible contact and the cylinder. Bushing inserts also include a current conducting connection to another component of the distribution system, such as to the threaded stud of a bushing well as disclosed in U.S. Pat. No. 4,353,611. While current carrying connections are necessary in a bushing, they can also be a cause for damage and failure due to loosening or corrosion, leading to faulty conduction and overheating. After damage, it is desirable that all current conducting components be replaceable within a bushing. While prior art bushings have provided for replacement of the female contact and of the metal piston, prior art has not provided a bushing wherein all current conducting components of the bushing are replaceable within the bushing housing. U.S. Pat. No. 4,202,591 is an example of such prior art, wherein the female contact is the only load current conductive component that is readily removable from the bushing insert 30.